1. Field of the Invention
This invention relates to an addition curable adhesive organopolysiloxane composition.
2. Description of the Prior Art
Addition curable adhesive compositions comprising an organopolysiloxane having a silicon-bonded vinyl group as the principal agent have been known in the art, but these compositions are not still insufficient in adhesiveness, and have drawbacks such that the cured product may be peeled off from the substrate in, for example, impregnation potting for coating electrical parts, etc.
For the purpose of eliminating such drawbacks, it has been proposed to use various adhesion imparting agents (Japanese Patent Publication (KOKOKU) Nos. 13508/1978, 21026/1978, 5219/1974).
However, in the prior arts as mentioned above, although adhesion performance may be improved to some extent, its adhesion durability is still insufficient, and if the adhered product is maintained under severe conditions such as in water, etc., peep-off will frequently occur.
Therefore, an object of the present invention is to provide an addition curable adhesive organopolysiloxane composition improved markedly in adhesion durability.
The present invention has successfully improved markedly adhesion durability by use of a compound having two or more allyl ester groups in its molecule for compositions known in the art.
More specifically, the addition curable adhesive organopolysiloxane composition comprises:
(A) 100 parts by weight of an organopolysiloxane having at least two alkenyl group in its molecule and a viscosity at 25.degree. C. of 100 to 200,000 cSt,
(B) an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms in its molecule in such an amount as to supply 0.6 to 6.0 silicon-bonded hydrogen atoms per alkenyl group of said (A) organopolysiloxane,
(C) a catalytic amount of a platinum catalyst,
(D) 0.5 to 20 parts by weight of an adhesion imparting agent comprising a silicon compound having at least one group selected from the group consisting of an alkoxy group and an epoxy containing hydrocarbon group and also having one or more silicon-bonded hydrogen atoms in one molecule, and
(E) 0.05 to 5 parts by weight of a compound containing two or more allyl ester groups in its molecule.
The adhesive organopolysiloxane composition of the present invention can be adhered alone easily and firmly to not only metals but also to various plastics such as polyethylene terephthalate, polybutylene terephthalate, phenol resin, epoxy resin, etc., and yet adhesion durability is markedly improved.
Therefore, in accordance with the present invention, it has become possible to apply an addition curable adhesive organopolysiloxane composition to extremely wide various uses.